Sir, could you make a few to sell, I'd order a custom one.

How can such a small battery spot-weld

I just got one too, welding 18650 cells it's fine,

Should have opened it up to see what battery is inside

There's a Zhiban S1 in the top-left of the video, how do you use it?

Not durable

AWithZ welders are good. I bought this one before too, the welds are rock solid, fine for small welding jobs. Later when I needed more welding power I bought their supercapacitor model, the UF20B